Process of making pulp



Patented Feb. 11, 193C.

UNITED STATES PATENTW, OFFICE.

SIDNEY D. WELLS, F QUINCY, ILLINOIS, ASSIGNOR TO PAPER MILL LABORATORIES,

INC., 01 QUINCY, ILLINOIS, A CORPORATION OF ILLINOIS PROCESS OF MAKING PULP pulp whereby the chemicals with which the pulp is treated are not only saved in part but form the basis of a loading material and the colloidal matter is flocculated to add substance and rigidity to the product and at the same time render it waterproof.

As a result of the present improvement separation of chemical from pulp is rendered unnecessary, and stream pollution is avoided because the amount of waste chemical is lessened.

One of the features of the invention is the coagulation of colloidal matter of a gelatinous'organic nature and this is accomplished directly in the pulp mass. As a result of such treatment and the fact that colloidal matter is flocculated and is not removed the total final amount of product is greater than with the pulp alone and the product is characterized by peculiar toughness. Another feature pertains to the precipitation of mineral matter used during the cooking operation by means of first adding acid substance and then by means of alkali added after the acid treatment. Upon addition of an acid or an acid salt considerable quantity of gelatinous organic matter is precipitated and which acts as both a loading material and a sizing material. a

A further advantage is derived by the saving in equipment in which washing machinery may be eliminated or greatly reduced, and attention to cylinder andFourdrinier wires may be made less frequently, thus saving time, apparatus, and providing a gain in production.

In the manufacture of board and paper products from cereal straws and other vegetable'fibrous material, it is customary to soften the material bydigesting it with suitablecooking agents such as calcium hydroxide and after it has been removed from the cools ing vessel and allowed to remain in a pile fora suitable time to wash the pulp until the cooking residues have been removed so far 1926. Serial No. 121,052.

as is possible. This practice has led to serious complaint on account of pollution of the streams and besides was very wasteful of fiber and other substances from the straw which should be utilized in the paper.

It has now been found that byadding an acid or acid salt such as sulphuric acid or sodium acid sulphate to the unwashed or only partially washed material as it is disintegrated to its ultimate fibers in beaters, re-

' finers or other devices known to the art, the

alkalinity may be neutralized and the alkaline base used rendered soluble in water or converted to a loading material such as calcium sulphate which can be left in the finished product. Aluminum sulphate can be advantageously used in conjunction with the acid or acid salts, and when so used should be added after the major part of the neutralization has been accomplished. Also, hydrochloric acid may be used as the acid material and aluminum sulphate may serve as the acid salt.

Where a waterproofed product is desired it is preferable to use a very eficient flocculating agent, namely aluminum sulphate, to complete the acidification of the mass and the flocculation of the colloidal matter. lhis preference holds whether lime be used as the cooking medium or whether there be used much more soluble reagents such as sodium carbonate, sodium sulphide, sodium hydroxide, or sodium sulphite. The amount of 'alum- (aluminum sulphate) required dependson the hydrogen ion concentration of the mass and can be reduced to a minimum if a considerable proportion of the alkalinity is first neutralized by the use of acids or acid salts cheap in price such as sulphuric acid or nitre cake (sodium acid sulphate). With straw cooked with 180 pounds of sodium carbonate and 18 pounds of sulphur per ton of product and washed one hour in a typical beater provided with two drum washers 100 pounds of nitre cake and 50 pounds of alum per ton of product gave a waterproofed board .025 thick which held water twentyiour hours without seepin through. I v

Sulphate of iron may e used in lieu of aluminum sulphate and is a cheaper mate rial. use, however, is limited to conditions in which the color of the iron compound is not objectionable.

, The residues formed when lime is used are largely CaCO, and compounds of calcium wi organic acid. F orinstance, thereaction between calcium carbonate and sulphuric acid is merely typical and approximately a 7 follows: 7

CBCO; CaSO, 00 +HgO- alkali depending on the acid or acid salt used.

Thus, if sulphuric acid or an acid sulphate be used, there will be produced sulphates in the final product, whereas if hydrochloric acid is used, chlorides will be formed. The coagulant chosen depends, to some extent, on

products obtained. The use of hydrochloric acid is for the purpose of neutralizing the whole or a major ortion of the calcium carbonate and any ree calcium hydroxide as cheaply as ossible; Aluminum sulphate would do it, ut at such an increase in exnsc when used alone as to be prohibitive.

en sodium acid sulphate is used as the neutralizing agent, ordinary hydrated lime will serve as the coagulant and we have the reaction Na so.-oa02H, 2NaOH-CaSO,. When sulphuric acid or hydrochloric acid are used for neutralization in the absence of sodium salts sodium hydroxide has been found most efiective. If soda salts are present, and either sodium hydroxide or hydrated'lime is added, there will be a resultant precipitation of magnwium hydroxide which will sweep the solution clear on settling, assuming that the lime of the cooking agent is average commercial lime or a dolomitic lime.

It has also been found that if acid is added until an indicator such as methyl red shows an acid reaction and alkali is thenadded after the acid has been thoroughly mixed with the stock until phenolphthalein shows an alkaline reaction, that satisfactory results are obtained. Under these conditions a non-waterproof product is obtained. The use of aluminum sulphate as heretofore mentioned assists in the coagulation and renders it more positive and capable of accomplishment between wider limits. The precipitated aluminum hydroxide is also desirable as a filler in the paper and, if used until an acid condi-* t, in which the fibrous material tion is obtained, it will render the product waterproof.

I claim 1. The process of treatin vegetable fibrous material to prepare it or use in paper products which process includes digestin the fibrous material with a chemical coo ing agent, and after cooking, subjecting the cooked material to a mechanical disintegration treatment and in lieu of washing adding an acid material after disintegration of the cooked material has commenced and thereby neutralizing alkalinity and retaining the neutralized material in the mass.

2. The process of treating vegetable fibrous material to prepare it for use in paper products which process includes digesting the fibrous material with a chemical cooking agent, and after cooking, subjecting the cooked material to a mechanical disintegration treat-' ment and in lieu of washing adding an acid material after disintegration of the cooked material has commenced and thereby neutralizing alkalinity, adding aluminum sulphate after neutralization is well effected, and retaining the resultant insoluble products with the neutralized material in the mass.

3. In the treatment of vegetable fibrous material with an alkaline digesting agent, the process of recovering colloidal matter in the digesting li%uid whlch process includes digesting the lbrous material with a chemical cooking agent and after cooking, subjecting the cooked material to a mechanical disintegration treatment and after the disintegracommenced, the process of recovering colloidal matter in the resulting digesting li uid, which process includes the addition 0 an alkali to the digesting liquid after neutralization with an acid material and the coagulation thereby of colloidal matter.

5. In the treating of vegetable fibrous material with an alkaline digesting agent to prepare it for use in paper products the process which includes treating it with an alkaline digesting agent, subjecting the fibrous material after it has been treated with said alkaline digesting agent to a mechanical disintegration treatment, then after disintegration of the cooked material has commenced adding acid material until the chemical shows an acid reaction, and then adding an alkali until the material shows an alkaline reaction, and retaining the neutralized material in the mass with the vegetable fibrous matter.

6. 'I he process of treating vegetable fibrous material to prepare it for use in paper products which process includes digesting the fibrous material with a chemical cooking agent, and after cooking subjecting the cooked material to a mechanical disintegration treatment and in lieu of Washing adding an acid material after disintegration of the cooked material has commenced and thereby neutralizing alkalinity and rendering the alkaline base soluble in Water.

7. In the production of paper products from fibrous plant material, the process of treatment which includes digestion with a chemical cooking agent, after cooking subjecting the cooked material to a mechanical disintegration treatment and in lieu of washing retaining in the material treated the natural waterproofing substances, and coagulating the natural waterproofing substances by treating the same with an .acid material and a coagulating agent, said acid being added after disintegration of the cooked material has commenced.

8. In the production of paper products from fibrous plant material, the process of treatment which includes digestion with a chemical cooking agent, after cooking subjecting the cooked material to a mechanical disintegration treatment and in lieu of washing retaining in the material treated the natural waterproofing substances, and coagulating the natural waterproofing substances by treating the same with an acid material and alum, said acid being added after disintegration of the cooked material has commenced.

9. In the production of paperproducts from fibrous lant material, the process of treatment Wh1ch includes digestion with a chemical cooking agent, after cooking subjecting the cooked material to a mechanical disintegration treatment and in lieu of WaSl1' ing retaining in the material treated the natural waterproofing substances, and coagulating the natural waterproofing substances by means of a material including alum, said acid being added after disintegration of the cooked material has commenced. v

In testimony whereof I affix my signature.

SIDNEY D. WELLS. 

